In a changing and complex world, we require the ability to sustain pursuit of a goal, while also updating our goals as the need arises. For example, we are capable of rapidly shifting tasks, such as stopping work on a paper to have an involved discussion with a colleague. However, we are also able to avoid distracting cues, such as ignoring the unread e-mail messages incrementing in our inbox while we write. The mechanisms by which the brain achieves an adaptive balance between flexibility and stability remain the basis of much current investigation in cognitive neuroscience. In PNAS, D’Ardenne et al. (1) provide evidence for two key pieces to this puzzle. They demonstrate that the dorsolateral prefrontal cortex (DLPFC) is necessary for flexible updating of contexts to control behavior and that activity in cells of the dopaminergic midbrain may signal an updating response.

One solution to the flexibility vs. stability paradox has been to hypothesize a working-memory “gate.” Such models assume that working memory, supported by PFC, maintains contextual information to modulate thought and action (2). Critical to such a system is a mechanism by which useful contextual information is updated into working memory and distracting information is kept out; in other words, a working-memory gate. When the gate is open, available information can enter working memory. When the gate is closed, the current contents of working memory are sustained, while irrelevant information is kept out.

Having separate maintenance and gating mechanisms is computationally efficient (3). And, although there are proposals of general form recurrent networks with diverse neural responses (akin to those in PFC) that can exhibit self-gating behavior (4), the most influential models of working-memory updating assume separate gating and maintenance mechanisms (5, 6). Specifically, the PFC is proposed to support noise-resistant maintenance, such as via recurrence …

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